Arc lamp



Jan. 5, 1943. J, GELB ARC LAMP Filed Sept. 4, 1940 4 SheetsSheet l L 'INVENTOR Az'zamvz'f,

Jan. 5, 1943. J. GELB 2,307,260

' ARC LAMP Filed Sept. 4, 1940 4 Sheets-Sheet 2 f, I I

Z i MENTOR BY ,Z[;

J. GELB Jan. 5, 1943.

ARC LAMP ,Filed Sept; 4, 1940 4 Sheets-Sheet 5 I 9x 4/ 0 Z 70 a 0 ,0 1 w -P Z [L H FF a Z 5 fi 4 m a p,

' GELB Jan. 5, 1943.

ARC LAMB Filed Sept. 4, 1940 4 Sheets-Sheet 4 g IN E ZNTOR.

Patented Jan. 5, 1943 UNITED STATES PATENT OFFICE ARC LAMP Joseph Gelb, New York, N. Y.

Application September 4, 1940, Serial No. 355,281

4 Claims.

The invention which forms the subject matter of the present application is an improvement in an arc lamp particularly adapting the same for photographing and other purposes where constant light value is required. In lamps of the character referred to, carbon electrodes are employed.

V The particular object of the invention is to provide an improvement upon the arc lamp, subject of my Patent No. 2,204,079, in that it provides in combination with a pair of movable electrode carriers and electrically operated means for automatically controlling their movement toward and from each other, of counter balance means for said carriers characterized by a variable action upon the carriers in accordance with the position thereof.

Specifically the construction is such as to employ a bell crank lever having one arm in operative engagement with the walls of a raceway on one of the electrode carriers and a weight carried by a second arm of the bell crank lever in such position as to efiect a gradually decreasing gravitational separating force upon the ectrode carriers as the latter move toward each other through burning of the carbon electrodes. However, the form of the embodiment herein illustrated may be modified without departing from the spirit of the invention.

The invention will be described with reference to the accompanying drawings, in which:

Figure 1 is a side elevation view, partly in section, of the improved arc lamp, the lamp holding carbons of long length.

Figure 2 is an enlarged view in elevation, show- 3 Figure 6 is a vertical sectional view similar to Figure 4, the view being taken however from the side opposite that shown in Figure 4, and the casing being modified.

Figure '7 is a top plan view of the structure shown in Figure 6.

Figure 8 is a view in elevation, partly in vertical section, illustrating the clutch and dash pot construction.

Figure 9 is a fragmentary horizontal section taken on the line 9-9, Figure 8.

Figure 10 is an elevation, partly in section, the section being taken on the line l0-l0, Figure 19.

Referring to the drawings, it will be noted that the reflector R is arranged at one side or laterally of the pair of hell crank levers carrying the electrodes. The long arms of the opposing bell crank levers L are pivoted on the spaced fulcrum pins I attached to the standard 2 (Figure 1) of the bracket or supporting frame generally designated F. Short arms Lw, Lxa: extending from the bell crank levers L are interconnected by a pin and fork connection consisting of pin 3:: extending from arm Lzr and the fork 4 straddling pin 3:: and extending from the adjacent short arm Lmx.

By mounting the crank levers in the manner shown, the distribution of forces applied to these levers whether the reflector and the supporting means 3 be tilted or whether not tilted, is substantially the same, that is, the distribution of these load forces on these hell crank levers substantially neutralize each other and consequently these levers may be considered as balanced. It follows therefore that an appreciably less load is applied to the retractible armature of the electrical control means hereinafter more par ticularly set forth, thus providing more sensitivity in the matter of actuating these levers.

It will be observed that each of the bell crank levers is provided with a hollow holder 5, each sustaining a carbon electrode C electrically connected to cables 6 attached to the long arms L of the bell crank levers as shown in Figure 1. The upper cable 3 is electrically connected to one end la: of solenoid I. The other end of the solenoid and the lower cable are suitably connected to a source of electrical potential by means of a similar conduit 8. The winding of the solenoid, the cables and the electrodes are in series in the same circuit.

Depending from shoe 922 of the retractible armature 9 are the spaced apertured posts to through which the outer convolution of a relatively flat spirally coiled stabilizing and shock absorbing spring H is threaded. In one form, the inner convolution of spring ll is secured to a depending and centrally arranged stud [2 which is connected to a lever 14 by means of 1. l3, the latter passing through an elongated slot in the lever. The said lever i4 is pivotally connected at l5 to the frame F.

The front end of the lever i4 is attached to the top lug of an inverted dash pot l5 having a piston P, and is pivotally connected to the dash pot by a transverse pin [6. If, therefore, the solenoid. is energized, the core thereof attracts the armature 9 causing lever M to rise. It also follows that the dash pot I5 is raised at this time.

Interposed between a clutch block l1 and the lever I4 is an elastic and shock absorbing connection. The elastic connection may be (as shown in Figures 6, '7, 8 and 9) formed by a relatively fiat spring 2|], to the outer convolution of which will be fastened a bracket 2|, as shown more particularly in Figure 10, the bracket being formed with an upwardly projecting lug carrying fulcrum pin 25 pivotally sustaining the end of arm 26 to which the clutch I8 is attached.

Clutch I8 is provided with a slot having faces which will be formed at an incline in respect to the curved faces of the arcuate arm Hi. The elastic connection is such that when lever M (Figure 6) is pivotally displaced, clutch I3 is actuated through the adjustable link 21 which will have its upper section fixedly fastened to the inner convolution of coiled spring 2!) and its lower section connected at 28 to the lever Hi.

When the solenoid 1 is energized clutch l8 first slightly moves relative to the arcuate arm i9 and subsequently the inclined faces of its opening grip the arcuate depending arm l9, causing the latter to be elevated and consequently the long arms L of the bell crank are separated by reason of the fact that said arcuate arm I9 is carried by the uppermost of the arms. limit of any given movement of arm i9 is controlled by the adjustable screw 23 which serves as a stop for the clutch l8.

Appropriately fastened to an arm of the standard F is a plate 32 (Figures 3 and 4) having integral therewith the offset arm 33 attached to reflector R to which in turn may be fixedly attached a shield or flame protectorindicated by dotted lines at 34, Figure 4, and serving to protect the operator from the glare of the are or flame created between the poles of the electrodes Secured to the refiector R is a socket bracket 35 (Figure 1) in which is fixed a shaft 36, journalled in the bearing of a yoke comprising an arm 3'! and an arm 39. In practice, the two yoke arms 31, 39 carry a collar 49 adapted to be carried by a post 4! which may be slidingly received in a suitable hollow standard. A clamping device may be carried by the standard to serve to hold the post in vertically adjusted position.

An adjustable hand wheel 42 is threadably connected to a stud shaft 40:0 carried by the frame 3 and supported by arm 39 of the yoke. Hand wheel 42 serves to hold shaft 40:10 in a set position after the reflector has been tilted, as is well understood.

The operating mechanism for actuating the bell crank levers shown in Figures 1, 4 and is disposed in a casing or housing 43 which is secured to and surrounds the supporting frame F. The operating mechanism within housing 13 together with the reflector R may be considered for purposes of specification as a unitary device rotatably sustained in members 31 and 39. Accordingly this unitary device may be readily tilted bodily relative to its supporting yoke. After rotation to a desired position, the unitary device will be held in such set position due to the hold- The-- ing action of the hand wheel 42 against the yoke.

Each of the carbon holders 5 although secured to a bell crank lever is also insulated therefrom and in this connection it will be noted that terminals of each of the bell crank levers has attached to opposite faces thereof, layers of mica M (Figure 1).

The electrode carrying arms L being interconnected and arranged to tend to bring the carbon electrodes into contact throughout the operation of the lamp, it follows that in the absence of the solenoid or other control for the arms, the carbon electrodes would be maintained in contact at their ends. The function of the solenoid or other control is to maintain the electrode gap constant and at that degree best designed for proper illumination. In starting the lamp, the contact of the electrodes effects a heavy amperage through the solenoid, the core 9 being forced inwardly, raising levers M and link 21, clutch I8 acting on arcuate arm [9 to separate the bell crank arms L against the heavy gravitational force tending to move them toward each other. In this way the proper gap is secured.

Difficulty has been encountered in past constructions, however, because in starting illumination with the arms widely separated and holding long and heavy carbon electrodes, the gravitational action is such as to require relatively higher amperage through the solenoid winding in order to raise the bell crank arms and secure and maintain the gap. In such case, as the carbons burn, the amperage through the solenoid is lowered and the amperage passing to the carbon electrodes is correspondingly increased, producing a more intense light. For such reason it has been necessary in the past to limit the size of the carbon electrodes, or else suffer the marked disadvantage of gradually increased light intensity.

To cure the defect above stated, I have applied variable counter-balancing means for the electrode carrying arms L which will act to maintain the amperage through the solenoid, or a motor control, when used, constant. For this purpose a lever arm BI is fixedly secured to a shaft 62 extending through a suitable aperture formed in frame F (Figure 1), the shaft fixedly carrying a depending arm 63 which carries a stud 64 disposed within a raceway formed by the upper face of the lower arm L and a rod or bar 65 carried by blocks 66 fixed to said lower arm L. The outer end of lever arm 6| carries a weight 61. This weight is so positioned that when the bell crank arms L are widely spread, the weight through lever arms BI, 63, exerts a force tending to balance the increased gravitational force on the arms. As the carbon electrodes are consumed the gravitational force required to separate the arms is decreased and the weight is raised until it finally reaches a dead center position with respect to its axis at 62. Thus as the carbon electrodes are consumed, the force exerted by the weight is progressively decreased, and when the carbon electrodes are at short trim the weight is so positioned as to have little or no action.

It will be understood that ftll trim carbons, and thus of maximum weight, may weigh, for example, 16 ounces for the pair, and their consumption will gradually reduce the weight until, for example, the lamp is operating with carbons having a combined weight of only 3 ounces. The

invention overcomes the problem arising from this factor.

In Figures 6 and '7, the casing and reflector are joined as a common closed housing for the electrode carriers. To this end the casing, shown at 43a: is outwardly flared at the side joining the reflector R and the flared area of the casing is flanged for Welding or riveting to the reflector, as desired. The electrode carriers thus operate wholly within the enclosure thus provided.

In some types of arc lamps a fixed electrode carrier operates in conjunction with a movable electrode carrier, and the invention is equally applicable thereto. In such case the counter balance means will act in conjunction with the movable carrier. Usually the lowermost electrode carrier is the one which is fixed and the uppermost electrode carrier is movable and provided with electrically operated means for automatically controlling its movement and by means of the present invention the uppermost carrier will be counter balanced by a variable action in accordance with the position thereof, and the counter balancing force will be progressively decreased as the electrode carrier by the uppermost and movable carrier is burned off.

Having described my invention, what I claim and desire to secure by Letters Patent is as follows:

1. In an arc lamp employing carbon electrodes and in combination with a pair of movable electrode carriers, means for automatically controlling their relative movement, counterbalance means for said carriers characterized by variable action on the carriers in accordance with the burning off of the carbon electrodes and the loss of weight by such burning off, said counterbalance means comprising a weighted movable member operatively connected to one of the carriers and movable with and also relatively thereto.

2. In an arc lamp employing carbon electrodes and in combination with a pair of movable electrode carriers, means for automatically controlling their relative movement, a raceway on one of the electrode carriers, a lever having a sliding engagement with the walls of said raceway, and a counterbalance engaging said lever.

3. In an arc lamp employing carbon electrodes and in combination with a pair of movable electrode carriers, means for automatically controlling their relative movement, a raceway on one of the electrode carriers, a bell crank lever having one arm in operative engagement with the walls of said raceway and a weight carried by a second arm of the bell crank lever in such position to efiect a gradually decreasing gravitational separating force upon the electrode carriers as the latter move toward each other through burning of the carbon electrodes.

4. In an arc lamp the combination with a pair of supported movable electrode carriers and a solenoid operated clutch adapted to control the movement of said electrode carriers in accordance With the burning off of the electrodes, the electrode carriers being interconnected and mutually counterbalanced, of means acting upon the carriers with a pressure tending to move them away from each other, the said means being adapted to act to gradually decrease said separation pressure as the carriers move toward each other in the burning off of and loss of weight in the electrodes.

JQSEPH GELB. 

